A083224 a(n) = (6*7^n + (-7)^n)/7.

1, 5, 49, 245, 2401, 12005, 117649, 588245, 5764801, 28824005, 282475249, 1412376245, 13841287201, 69206436005, 678223072849, 3391115364245, 33232930569601, 166164652848005, 1628413597910449, 8142067989552245

Offset: 0

Author

Paul Barry, Apr 23 2003

Keywords

• easy
• nonn

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..300
• Index entries for linear recurrences with constant coefficients, signature (0,49).

Crossrefs

Cf. A083223, A083225.

Programs

Magma

[(6*7^n+(-7)^n)/7: n in [0..25]]; // Vincenzo Librandi, Jun 29 2011

Mathematica

LinearRecurrence[{0,49},{1,5},30] (* Harvey P. Dale, Oct 12 2018 *)

Formula

a(n) = (6*7^n + (-7)^n)/7.

G.f.: (1+5*x)/((1+7*x)*(1-7*x)).

E.g.f.: (6*exp(7*x) + exp(-7*x))/7.